Cryoliquid pump



Feb. 21, 1967 J R T 3,304,882

' RYOLIQUID PUMP Filed June 5, 1964 3 Sheets-Sheet 2 NVENTOR JAMES D.YEAROUT United States Patent 3,304,882 CRYOLIQUID PUMP James D. Yearout,Waynesboro, Va., assignor to The La Fleur Corporation, Los Angeles,Calif., a corporation of California Filed June 5, 1964, Ser. No. 372,7476 Claims. (Cl. 103-153) The present invention relates to a reciprocatingmultiple piston pump adapted to be secured to the wall of a container ofliquid so as to have its pump cylinders and pistons inside the containerand immersed in the liquid to be pumped, and to have the pump rodsextend out of such liquid and such container for connection to theiractuators; the liquid to be pumped being such as nitrogen, oxygen,helium, or hydrogen under low pressure and at very low temperature, andsuch liquid to be pumped against either low or high heads. Such liquidsmay be called cryoliquids.

Pump construction of this kind and for this purpose has had the problemsof inlet pressure drops causing the formation of gas in the pumpcylinders, and much trouble, due to frosting, in maintaining a gas andliquid seal along pump rods where they leave the container, the zone oftransition from the low temperature of the liquid to the ambienttemperature surrounding the container. Also, it has been a problem induplex pumps to maintain the two pistons in step and in full stroke.Reliability and simplicity are of prime importance in pumping suchliquids as pump failures may result in serious losses of liquid, and indamage to other equipment. 7

For the above reasons, it is an object of the present invention todevise a pump for loW temperature liquids that has inlet checks andpassageways that oifer negligible resistance to liquid flow.

Another object of the invention is the devising of a pump shaft heatingmeans and insulating construction that prevents the formation of froston the shaft, its bearings, and its seals so that the bearings and sealswill have a long operational life.

A further object of the invention is the construction of a synchronizinglinkage for a duplex pump that insures the pumps staying in step and atfull stroke. It is, also, an object to apply such synchronizing means toa hydraulic drive for such duplex pump.

The above mentioned defects of the priorart are remedied and theseobjects achieved by a reciprocating piston pump construction having amounting flange about midway of the length of the pump assembly that issecurable to the inner wall of an insulated container, or vessel, sothat it surrounds an opening in such wall located adjacent the bottom ofthe tank, with the pump pistons and cylinders inside of the wall andportions of the pump rods and the pump actuators outside of the wallwith partitions and seals along the shafts to prevent the leakage ofliquid or gas along such rods.

Intake head loss is reduced to a negligible amount by making the intakeopening of substantially'the same area as the piston area, and by theuse of an inlet check valve that moves aside and away from its seat toleave the opening free for liquid flow, and by the inlet passage beingshort and in direct communication with the body' of liquid in thecontainer.

Frosting along the pump rods is prevented by the rods being long enoughto extend from the inside of the container to well outside thereof toprovide a heated isolating length of and for each rod. This isolatinglength is heated by the circulation of gas from .such liquid in achamber around a rod and along such insulating length. This circulationis effected by an annular piston secured to such length, such pistonreciprocating in such chamber to surge the gas thru a heating coilexternal of the chamber.

The pump is provided with one double acting piston for use in pumpingagainst low heads, and two single acting pistons of relatively smalldiameter with respect to the single low head piston, for use in pumpingagainst high heads. The three pistons and their cylinders, and'theirpiston rods are contained in a single housing. A separate hydraulicdrive cylinder is associated with each of the piston rods, and the twohigh pressure pump rods are provided with cross connected linkages thatcontrol the admission of drive fluid to the drive cylinders so that thehigh pressure pistons stay in step and so that each one has maximumstroke. The arrangement of the two high pressure pumps and theiractuating cylinders, and their control linkage is similar to that ofmany duplex pumps. Each pump rod is provided with a control cam thatcontacts a cam follower as it reaches each end of its stroke. The camfollowers associated with each cam are secured at opposite ends of arocker, and two adjacent ends of the rockers are linked to opposite endsof a floating lever that is midconnected to a control valve, or pilotvalve, for a main hydraulic valve. With this arrangement, the controlvalve is never in either of its extreme positions until both pump rodshave moved to their extreme positions. Thus, the flow of motive fluid isnot reversed until both piston rods have reached the ends of theirstrokes.

The cryoliquid pump construction briefly outlined above is hereinafterdescribed in detail and illustrated in the accompanying drawings, inwhich:

FIGURE 1 is a cabinet view of the pump assembly.

FIGURE 2 is an isometric view of a portion of the pump base showing oneof the high pressure pumps in quarter section with the pump rod brokenaway.

FIGURE 3 is an isometric view in quarter section of a shaft heater unitwith the pump rod broken away on both sides of the unit.

FIGURE 4 is a schematic line drawing of the entire pump assembly and thecontrols therefor.

The pump assembly is shown in a physiml embodiment illustrated in thecabinet drawing of FIGURE 1, and is diagrammed in the schematic linedrawing of FIGURE 4. The following description refers to both of thesefigures. The complete assembly is a unit that may, for the purpose ofconsideration and description, be divided into four sections: pump,heater, control, and drive. The pump section is placed inside of andadjacent the bot-tom of a tank that contains the cryoliquid to bepumped. The rest of the assembly is outside of the tank. S-uch tank isnot shown. The assembly is secured to a tank wall and in an openingtherein that is of a size and shape to fit inwardly of a pump mountingflange 11. The tank flange 11 has a circle of bolt holes 12 that alignwith bolt holes in the tank so that bol-ts thru the aligned holes maysecure-the assembly to the tank wall with the section to the right, inthe figures, of the flange, the pump section, inside of the tank. Theflange extends across the pump to seal the tank opening except forpacked openings in the flange for the output piping of the pump and thepump rods. A double acting piston 13 is housed in a cylinder 14. Thispiston is intended for pumping against low heads, and is of relativelylarge diameter as compared with two other pistons 15, 16 located belowand parallel to the low pressure piston and cylinder. These pistons areintended for use in pumping against much higher heads than those againstwhich the large piston operates. The cylinders 17, 18 for the highpressure pistons are part of a base 19 to which the low pressurecylinder 14 is bolted. The low pressure. cylinder has .a cap 21 that hasformed therein an inlet" opening having an inlet check 22 and an openingfor an outlet check 23. The base 19 is similarly provided with.

a low pressure inlet and check 24 and a low pressure outlet check 25.Each of the high pressure cylinders has an inlet check 27, 28 and anoutlet check 29, 30. The base 19 is spaced from and connected to themounting flange 11 by a frame that is concealed by a cover 31, and thisspace is used to insulate the pumps from the tank wall.

To the left of the mounting flange 11 are a pump rod heater section anda pump control section, both in a housing delineated n FIGURE 1 by aseries of ribs 32 that extend parallel to the pump rods 33, 34, 35, ofthe pistons, and which ribs are joined together to form a cylindricalhousing for the shaft heaters and the pump controls. The right hand endof the heater housing is secured to the tank flange 11 and the otherend, the outer end, is closed except for the pump rod and pipingopenings therethru, and the outer end serves as a base for the hydrauliccylinders 36, 37, 38, one for each pump rod, that operate the pumps.Mounted on and exteriorly of the heater section 32 are three heatexchangers 39, 40, 41. A junction box 42 for the outlet piping of thepumps is located on the near side of FIGURE 1, the piping is not shown;and a similar box on the far side accommodates the control piping forthe hydraulic cylinders. The outlet pipe 43 for the near side highpressure piston is partially shown as are the outlet pipes 44, 45 forthe two ends of the low pressure piston. The outlet pipe for the farside low pressure piston i concealed by the view. All of these outletpipes pass thru the mounting flange 11 interiorly of its bolt holecircle but such has not been illustrated.

All of the inlet check valves 22, 24, 27, 28 are of the sameconstruction and size, and only one valve 28 in the inlet port of one ofthe high pressure pump cylinders 18 will be described, as illustrated inFIGURE 2 in the quarter section isometric view of a portion of the base19 from the back side of FIGURE 1. The check disc 51 that closes theport is pivoted to the inner end of a U-shaped check arm 52 that has itsouter end pivoted in a slot in a flange 53 integral with one end of asleeve 54 whose other end acts as the seat for the check disc 51. Theflange 53 is bolted and sealed to the face of the base 19. The bore ofthe sleeve 54 forms the pump inlet, and the sleeve'is coaxial of thecylinder 18 and the piston 16 therein. The construction and operation ofthe check is such that as the piston moves from the check, liquid flowsinward thru the port to move the disc off its seat. The U-shaped armpivots in the flange asymmetrically of the sleeves axis, and its discend moves inward of the cylinder and upward until it contacts the sleevewall. The cylinder arjacent the seat is annularly relieved so that apart of the disc may move upwardly into this relieved area 56, and thelower portion of the disc may swing inwardly, movement in two degrees offreedom. The inward and upward movement of the check disc is sufficient,with the annular relief 56, to allow fluid flow with negliga'ble head.The outlet check 30 is not shown in detail but is placed in the outletpassage 57 that leads to an outlet pipe such as the near side one 43shown in FIGURE 1.

FIGURE 3 is an isometric view of a pump rod bearing and heater assembly,in quarter section, such as is associated with each of the three rods ofthe pump. The view is from the back side of FIGURE 1. The assembly isprovided with a bolt-ring mounting flange 61 that is bolted to the leftside of the pump mounting flange 11, and thru which one of the pumprods, 35 for example, extends, a portion only of the rod being shown inthis view. Secured to the flange 61 is a cylindrical sleeve 63 having aseries of spaced apart annular fins 64 integral with the exteriorthereof. The inner surface of the sleeve is spaced from the pump rod toform an annular bore between rod and sleeve. A sleeve bearing 66 issecured in the left hand end, in FIGURE 3, of the sleeve for the supportof the rod and to seal the left end of the bore. The right end of thebore is sealed by a packing ring 67. The rod carries a piston ring 68,and this piston ring is so placed that in the normal travel of the rodthe ring reciprocates, substantially, from end to end of the bore. Also,the piston ring is of a thickness to create a sliding seal between therod and the inside of the sleeve. Thus, as the piston ring reciprocatesin the bore it acts to pump any gas or liquid therein. The opposite endsof the bore are in communication thru a coil formed by a tube 69, andthe pumping action of the piston ring 68 forces such gas or liquid tooscillate or surge in the coil 69. Heat from an external source isapplied to the coil 69. The purpose of this construction is such thatany of the liquid being pumped that leaks past the sleeve bearing 66 iseither vaporized by being pumped into the hot coil 69, is vaporized bythe warmed surfaces in the bore, or is vaporized by the warm gas in thebore. Thus, there is no frosting of the pump rod 35, the bearing 66, thepacking ring 67, or the piston ring 68 as would occur if heat were notapplied to these parts and the liquid were to cool such parts byevaporation, and further liquid were to solidify on such parts due tosuch evaporative cooling. Such frosting would score the bearing, andwear and break the packing 67. Each of the heating coils 69 is containedin one of the heat exchangers 39, 40, 41 shown in FIGURE 1. Heat is alsoreceived by the sleeve 63 from the fins 64 attached thereto that receiveambient heat, and this ambient heat helps to prevent frosting at suchtime as the pump is not in operation but the pump is submerged in acryoliquid.

The operation and linkages of the pump drive controls are illustrated bythe schematic showing of FIGURE 4, rather than by views of the actualmechanisms. The controls are illustrated in the so labeled controlsection of FIGURE 4, and are found in the left hand portion of the cover31 of FIGURE 1. The two high pressure ump rods 34, 35 are in effectcross linked so that they stay in step, one with respect to the other.The low pressure pump rod 33 is independent of the other rods in itsoperation. Each of the rods is driven by a double acting hydraulic powercylinder 36, 37, 38, and these power cylinders are controlled by varioushydraulic valves actuated from cams secured to the pump rods.

The operation of the low pressure rod 33 control wilt be described firstas it is the simpler of the two controls. An annular shaped cam 71,illustrated as a ball, is secured coaxially of the pump rod 33. Theannular shape allows the cam to contact its followers regardless of therotation of the rod. Adjacent the rod is a follower rocker 72 that has apivot 73 medically of two followers 74, 75. The rocker and its followersare so shaped and placed that each follower is contacted in turn by therod cam as the rod reaches first one and then the other limit of itsstroke. This alternate contacting of the followers causes the rockerends to swing. To one end of the rocker 72 there is pivotally connectedone end of a link 77 whose other end is pin connected to the spool 05 ahydraulic pilot valve 78 so as to actuate said valve in unison with theactuation of said rocker. This pilot valve is hydraulically connected bylies 79, 80 with a master valve 82 that controls the admission anddischarge of pressurized hydraulic fluid thru the lines 83, 84, alter--nately, to opposite ends of the hydraulic drive cylinder 36 and tooposite sides of the piston 86 therein to effect reciprocation of suchpiston and its connected rod 33. The distance between the cam followers74, along the pump rod 33 determines the length of stroke of the rod andthe travel of both the drive piston 86 and the pump piston 13, as wellas the heater piston ring 68. The speed of pumping will, largely, bedetermined by the pressure of the hydraulic drive fluid delivered to thedrive cylinder 36 by the hydraulic control system.

The high pressure cryoliquid pumping pistons 15, 1.6 are controlled sothat their movement with respect to each other is sensed in oppositedirections and they reverse directional sense together. The highpressure pump rods 34, 35 are parallel to the low pressure rod 33, andall three hydraulic actuating cylinders are parallel and in opposition,

mounted in the same general location, the drive section. As illustratedin FIGURE 4, one of the drive pistons 91 is approaching the left handend, the front end, of its cylinder, and the other piston 92 isapproaching the back end of its cylinder, the right hand end. Each ofthe pump rods 34, 35 is provided at the control section with an annularcam 93, 94- concentric of the rod. Parallel to each rod is a pivotedfollower rocker 95, 96 having thereon followers 97, 98, 99, 100. Thisabove construction and operation of cams, and followers is the same asfor the low pressure control. As shown in FIGURE 4, the right hand endof each of the follower rockers 95, 96 is pivotally connected to one endof separate links 101, 102. The other end of one link 101 is pivotallyconnected to one end of a floating lever 103 and the other end of theother link 102 is pivotally connected to the other end of the floatinglever 103. The midportion of the floating lever is linked 104 to thespool of a hydraulic pilot valve 105 for actuation thereof. The pilotvalve 105 is hydraulically connected by lines 106, 107 to a master valve108 that controls the admission and discharge of pressurized hydraulicfluid alternately thru the lines 109, 110 to the front end of one andthe other of the drive cylinders 37, 38 and against the front side ofone and the other of the pistons 91, 92 to effect travel thereof towardthe back ends of their cylinders, and to effect pumping of thecryoliquid. The two cylinders are hydraulically cross connected adjacenttheir back ends. This hydraulic cross connection 111 effects the returnof the pistons to the head ends of the cylinders, one piston driving theother in the opposite direction by means of this cross connection 111.The cross linking of the controls for the two high pressure pump rodshas two purposes: first, it keeps the rods in step, and second, if fluidleaks from the cross connected back ends of the cylinders, eachhydraulic piston will lag in reaching the head end of its stroke untilthe other piston at the back end of its stroke has leaked fluid tocompensate for the lost cross connecting fluid.

With this construction, by the use of the floating lever 103, themidpoint of the floating lever has a path of travel along with the spoolof the pilot, and each end of the floating lever has a separate path oftravel. Each path has two extremes, the opposite ends of the path. Eachend of the floating lever moves from one end to the other of its pathupon a swing of its related follower rocker, but the midpoint of thefloating lever is not moved to an extreme position of its path untilboth ends of the lever have moved in the same directional sense. Thus,if one of the pump rods reaches its end of travel before the other one,the pilot spool is partially moved to reverse but not enough to causereversal of the pump rod travel. Reversal does not occur until the otherrod and the other end of the floating lever reach their extremepositions.

While the two high pressure drive cylinders are shown hydraulicallyconnected in series by the cros connection line 111, the disclosedcontrol linkages and hydraulic controls could be used with the drivecylinders hydraulically connected in parallel or with the drive pistonsbeing returned by spring means. Further, such construction are notdependent on the pumps being single or double acting, or dependent onthe two high pressure pump rod moving with the opposite directionalsense. The important aspect is that the control linkage provides a meansof insuring that both rods must reach their extreme positions before thecontrols reverse the directional sense of the rod travel.

The disclosed device may be used for pumping cryoliquids against low orhigh heads. The pump cylinders are immersed in the liquid to be pumpedso that vaporization and cavitation is eliminated or negligible. Theinlet check valves are of large area and offer negligible resistance toflow to reduce further the possibility of vaporization and cavitation.Simple and effective means are provided for heating the pump rodbearings and seals to eliminate frosting thereof. The control and drivemechanisms are simple and effective. Bearings, seals, controls, anddrive are located so as to be outside of the liquid tank and easilyaccessible for servicing.

Having thus described my invention, its construction and operation, Iclaim:

1. A shaft warmer for a shaft movable axially thereof, comprising: around shaft, a sleeve coaxial of and spaced from said shaft so that saidshaft and sleeve form therebetween an annular bore, means sealing theends of said bore to allow for axial reciprocal movement of said shaftin said sleeve, a piston ring carried by said shaft in said sleeve andsealing said bore between said shaft and said sleeve, and a conduitconnecting the opposite ends of said bore and having a portion extendingexternally of said sleeve whereby the fluid in said bore moves from oneend to the other as said shaft moves axially.

2. The combination of claim 1 including means for applying heat to saidconduit portion.

.3. A cryoliquid pump having an axially movable primary impeller forsaid liquid, a shaft carrying and driving said impeller, a housing forsaid impeller and said shaft with said shaft extending externallythereof, said housing forming an axially extending bore around andspaced from said shaft, spaced apart means sealing the ends of saidbore, a conduit external of said housing and having its opposite ends inspaced apart communication with said bore, and a secondary impellercarried by said shaft in said bore for circulating fluid thru saidconduit to the opposite ends of said bore as said shaft moves axially.

4. The combination of claim 3 including means for applying heat to saidconduit.

5. The combination of claim 3 including: a tank wall mounting flangesecured peripherally of and to said housing between said impellers.

6. In a cryoliquid pump, a housing, a shaft'in said housing, spacedapart shaft seals forming an enclosed space between said shaft and saidhousing, and permitting axial movement of said shaft, conduit means incommunication with and external of said space for allowing freecirculation of gas to and from said space through said conduit as saidshaft moves axially, and means mounted on said shaft intermediate saidshaft seals for inducing such circulation.

References Cited by the Examiner UNITED STATES PATENTS 262,119 8/1882Reynolds 103-49 695,989 3/ 1902 Worthington 103-49 2,507,895 5/1950Foxtow 277-22 2,851,860 9/1958 Lindsey 60-97 3,117,792 1/1964 Glenn eta1. 277-22 3,144,045 8/1964 Fitzpatrick 137-527.8 3,144,876 8/1964 Frye137-527.8 3,154,925 11/1964 De Vita 60-97 3,216,651 11/1965 King et a1.230-203 FOREIGN PATENTS 138,708 1/1953 Sweden.

57,132 7/ 1911 Switzerland.

DONLEY I. STOCKING, Primary Examiner. HENRY F. RADUAZO, Examiner.

3. CRYOLIQUID PUMP HAVING AN AXIALLY MOVABLE PRIMARY IMPELLER FOR SAIDLIQUID, A SHAFT CARRYING AND DRIVING SAID IMPELLER, A HOUSING FOR SAIDIMPELLER AND SAID SHAFT WITH SAID SHAFT EXTENDING EXTERNALLY THEREOF,SAID HOUSING FORMING AN AXIALLY EXTENDING BORE AROUND AND SPACED FROMSAID SHAFT, SPACED APART MEANS SEALING THE ENDS OF SAID BORE, A CONDUITEXTERNAL OF SAID HOUSING AND HAVING ITS OPPOSITE ENDS IN SPACED APARTCOMMUNICATION WITH SAID BORE, AND A SECONDARY IMPELLER CARRIED BY SAIDSHAFT IN SAID BORE FOR CIRCULATING FLUID THRU SAID CONDUIT TO THEOPPOSITE ENDS OF SAID BORE AS SAID SHAFT MOVES AXIALLY.